1. Field of the Invention
The present invention relates to an electric outboard motor. The present invention particularly relates to an electric outboard motor including an AC motor as a drive source and an inverter that supplies an alternating current to the AC motor.
2. Description of the Related Art
In recent years, an electric outboard motor is drawing attention to reduce the environmental load. For example, Patent Document 1 discloses an electric outboard motor including a motor as a drive source, a battery that supplies power to the motor, and a control unit that controls the motor. In the electric outboard motor, rotational force output by the motor is transmitted to a propeller through a drive shaft, a bevel gear, and a propeller shaft. The propeller rotates to generate driving force. The electric outboard motor also has a motor cover including a lower motor cover and an upper motor cover. The motor, the battery, and the control unit are accommodated in the motor cover. Since the exhaust gas is not discharged into water, the electric outboard motor can reduce the environmental load, compared to an outboard motor that includes, for example, an internal combustion engine as a drive source.
In a configuration with an AC motor as a drive motor, an inverter needs to convert a direct current supplied from the battery to an alternating current to drive the AC motor. Therefore, the inverter and the drive motor need to be electrically connected. If the battery is arranged on a ship separately from an outboard motor main body, the battery and the outboard motor need to be electrically connected by a connection cable. If wires or cables are routed in the outboard motor, a ship operator or a foreign matter may touch the wires or cables, and the wires or cables may be damaged.
In the electric outboard motor described in Patent Document 1, the control unit and the battery that are heavy in weight are arranged at positions away from the center of steering. The configuration increases a moment of inertia around a steering shaft, and great power is required for a steering operation. Therefore, the steering operation cannot be performed quickly. The control unit is arranged on the front side of the motor. Therefore, the control unit projects inside of the ship, and the space of the ship is compressed. Even if the control unit and the battery are arranged on the side of the motor, the moment of inertia around the steering shaft is not reduced. If the angle of steering is large, the control unit and the battery enter the space on the ship, and the space on the ship is compressed.
[Patent Document 1] Japanese Laid-open Patent Publication No. 2005-162055